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path: root/src/sim/drain.hh
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2015-07-07sim: Refactor and simplify the drain APIAndreas Sandberg
The drain() call currently passes around a DrainManager pointer, which is now completely pointless since there is only ever one global DrainManager in the system. It also contains vestiges from the time when SimObjects had to keep track of their child objects that needed draining. This changeset moves all of the DrainState handling to the Drainable base class and changes the drain() and drainResume() calls to reflect this. Particularly, the drain() call has been updated to take no parameters (the DrainManager argument isn't needed) and return a DrainState instead of an unsigned integer (there is no point returning anything other than 0 or 1 any more). Drainable objects should return either DrainState::Draining (equivalent to returning 1 in the old system) if they need more time to drain or DrainState::Drained (equivalent to returning 0 in the old system) if they are already in a consistent state. Returning DrainState::Running is considered an error. Drain done signalling is now done through the signalDrainDone() method in the Drainable class instead of using the DrainManager directly. The new call checks if the state of the object is DrainState::Draining before notifying the drain manager. This means that it is safe to call signalDrainDone() without first checking if the simulator has requested draining. The intention here is to reduce the code needed to implement draining in simple objects.
2015-07-07sim: Decouple draining from the SimObject hierarchyAndreas Sandberg
Draining is currently done by traversing the SimObject graph and calling drain()/drainResume() on the SimObjects. This is not ideal when non-SimObjects (e.g., ports) need draining since this means that SimObjects owning those objects need to be aware of this. This changeset moves the responsibility for finding objects that need draining from SimObjects and the Python-side of the simulator to the DrainManager. The DrainManager now maintains a set of all objects that need draining. To reduce the overhead in classes owning non-SimObjects that need draining, objects inheriting from Drainable now automatically register with the DrainManager. If such an object is destroyed, it is automatically unregistered. This means that drain() and drainResume() should never be called directly on a Drainable object. While implementing the new functionality, the DrainManager has now been made thread safe. In practice, this means that it takes a lock whenever it manipulates the set of Drainable objects since SimObjects in different threads may create Drainable objects dynamically. Similarly, the drain counter is now an atomic_uint, which ensures that it is manipulated correctly when objects signal that they are done draining. A nice side effect of these changes is that it makes the drain state changes stricter, which the simulation scripts can exploit to avoid redundant drains.
2015-07-07sim: Move mem(Writeback|Invalidate) to SimObjectAndreas Sandberg
The memWriteback() and memInvalidate() calls used to live in the Serializable interface. In this series of patches, the Serializable interface will be redesigned to make serialization independent of the object graph and always work on the entire simulator. This means that the Serialization interface won't be useful to perform maintenance of the caches in a sub-graph of the entire SimObject graph. This changeset moves these memory maintenance methods to the SimObject interface instead.
2015-07-07sim: Make the drain state a global typed enumAndreas Sandberg
The drain state enum is currently a part of the Drainable interface. The same state machine will be used by the DrainManager to identify the global state of the simulator. Make the drain state a global typed enum to better cater for this usage scenario.
2013-02-19scons: Add warning for missing declarationsAndreas Hansson
This patch enables warnings for missing declarations. To avoid issues with SWIG-generated code, the warning is only applied to non-SWIG code.
2012-11-02sim: Add drain methods to request additional cleanup operationsAndreas Sandberg
This patch adds the following two methods to the Drainable base class: memWriteback() - Write back all dirty cache lines to memory using functional accesses. memInvalidate() - Invalidate memory system buffers. Dirty data won't be written back. Specifying calling memWriteback() after draining will allow us to checkpoint systems with caches. memInvalidate() can be used to drop memory system buffers in preparation for switching to an accelerated CPU model that bypasses the gem5 memory system (e.g., hardware virtualized CPUs). Note: This patch only adds the methods to Drainable, the code for flushing the TLB and the cache is committed separately.
2012-11-02sim: Move the draining interface into a separate base classAndreas Sandberg
This patch moves the draining interface from SimObject to a separate class that can be used by any object needing draining. However, objects not visible to the Python code (i.e., objects not deriving from SimObject) still depend on their parents informing them when to drain. This patch also gets rid of the CountedDrainEvent (which isn't really an event) and replaces it with a DrainManager.